Please show the context surrounding the statement in question. Is it, by chance, the very first executable statement in the program? Was the statement "I = 0" already the current statement when you tried to place a breakpoint on it?

I tried several short programs with assignments of the type that you showed, and the debugger worked normally.

it only happens sometimes, and only if the sources that contain the subroutines in question are in a DLL file. I need to create an example which reproduces this consistently. I will post an update soon.